Image pickup apparatus and image pickup method

ABSTRACT

An image pickup apparatus and image pickup method, in which an image pickup area where a plurality of pixels each having at least first and second photoelectric conversion sections are arranged in a depth direction is used to pick up an object image, signals from the first and second photoelectric conversion sections are obtained in case that said image pickup area is light-shielded, and differential processing between a signal obtained in the first photoelectric conversion section in case that said image pickup area is light-shielded and a signal obtained in the first photoelectric conversion section by picking up an object image in said image pickup area, and differential processing between a signal obtained in the second photoelectric conversion section in case that said image pickup area is light-shielded and a signal obtained in the second photoelectric conversion section by picking up an object image in said image pickup area are performed, so that correction of image pickup signals is performed.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an image pickup apparatus andimage pickup method for picking up an object using a solid-state imagepickup element.

[0003] 2. Related Background Art

[0004] There is an image pickup apparatus such as a digital camera forelectronically or magnetically recording and reproducing on variousmediums still images or moving images picked up by a solid-state imagepickup element such as CCD and MOS sensor.

[0005] In order to reduce price or improve performance of such an imagepickup apparatus, there is an image pickup element (refer to FIG. 8) asdescribed in U.S. Pat. No. 5,965,875 where it is noted that a lightabsorption coefficient of a semiconductor substrate used in an imagepickup element is different according to a light wavelength.

[0006] In this patent, there are described a principle of an imagepickup element having a three-layer photodiode structure wherephotodiodes are formed with a triple-well structure, and a pixelcircuit. According to the patent, the photodiodes are sequentiallydiffused from a surface of a p-type silicon substrate, and an n-typelayer, a p-type layer, and an n-type layer are deeply formed in thisorder, so that pn-junction diodes are formed over three layers in thedepth direction of the silicon in the same pixel. As a light incidentinto the diode from the surface has a longer wavelength, it penetratesmore deeply. Since the incident light wavelength and the lightabsorption coefficient indicate a value specific to the silicon, acurrent is separately detected from the three-layer diodes, so that anoptical signal having a different wavelength band can be detected.

[0007] The depth of the pn-junction of the three-layer diode is designedso as to cover the wavelength band of a visible light. Three signals arecalculated so that signals where an object image is color-separated intothree colors of R color, G color, and B color can be obtained.

[0008] By the use of such an image pickup element, it is possible toeliminate a color filter for performing color separation of the objectimage or an optical low-pass filter for preventing moiré due to spatialsampling. Further, in the respective colors obtained by color-separatingthe object image, centers of gravity of sensitivity match with eachother, so that color moiré is advantageously difficult to be produced.

[0009] However, in the image pickup element for performing colorseparation in the depth direction of a semiconductor, when a noise ispresent, whose occurrence position is unstable in the depth direction ofthe semiconductor like a dark current, a different noise occurs for eachcolor even in the same pixel, thereby deteriorating the image.

[0010] Further, in the image pickup element as described above, amongthe three photodiodes corresponding to the respective colors in the samepixel, two photodiodes adjacent in the vertical direction arecapacitive-coupled to each other via the pn-junction. Further, ascharges generated in photoelectric conversion are accumulated in thephotodiode, the capacity of the photodiode changes. Therefore, apotential of a photodiode in one layer is influenced even by the amountof charges accumulated in other photodiodes. Further, when thephotodiode in the uppermost layer is saturated, the excess charges inthis diode are flowed into the n-type area of the photodiode in thelowermost layer beyond a potential barrier made of a second p-type layerfrom the top. Therefore, when there is a white defect or the like due toa local crystal defect of a semiconductor, even a color signal at thedepth where there is no defect is influenced, thereby deteriorating theimage.

SUMMARY OF THE INVENTION

[0011] The present invention is directed for solving the above problems,and it is therefore an object to provide an image pickup apparatus andimage pickup method capable of obtaining a good object image even when anoise such as a dark current different for each color occurs.

[0012] As one aspect of the present invention for achieving the aboveobject, the following structure is provided.

[0013] There is provided an image pickup apparatus comprising an imagepickup area where a plurality of pixels each having at least first andsecond photoelectric conversion sections are arranged in a depthdirection, and a first correction section for performing differentialprocessing between a signal obtained in the first photoelectricconversion section in case that the image pickup area is light-shielded,and a signal obtained in the first photoelectric conversion section bypicking up an object image in the image pickup area, and differentialprocessing between a signal obtained in the second photoelectricconversion section in case that the image pickup area is light-shieldedand a signal obtained in the second photoelectric conversion section bypicking up an object image in the image pickup area.

[0014] It is another object of the present invention to provide an imagepickup apparatus and image pickup method capable of obtaining a goodobject image even when there is a pixel defect which also influences acolor signal at the depth where there is no defect.

[0015] As one aspect of the present invention for achieving the aboveobject, the following structure is provided.

[0016] There is provided an image pickup apparatus comprising an imagepickup area where a plurality of pixels each having a plurality ofphotoelectric conversion sections are arranged in a depth direction, anda second correction unit for correcting each of signals from theplurality of photoelectric conversion sections arranged in the depthdirection in the same pixel to correct a defective pixel.

[0017] It is still another object of the present invention to provide animage pickup apparatus and image pickup method capable of obtaining agood object image without holding data for defect correction in advanceeven when there is a pixel defect which also influences a color signalat the depth where there is no defect.

[0018] As one aspect of the present invention for achieving the aboveobject, the following structure is provided.

[0019] There is provided an image pickup apparatus comprising an imagepickup area where a plurality of pixels each having at least first andsecond photoelectric conversion sections are arranged in a depthdirection, a first correction unit for performing differentialprocessing between a signal obtained in the first photoelectricconversion section in case that the image pickup area is light-shieldedand a signal obtained in the first photoelectric conversion section bypicking up an object image in the image pickup area, and differentialprocessing between a signal obtained in the second photoelectricconversion section in case that the image pickup area is light-shieldedand a signal obtained in the second photoelectric conversion section bypicking up an object image in the image pickup area, a second correctionunit provided in the rear stage of the first correction unit forcorrecting each of signals from the first and second photoelectricconversion sections arranged in the depth direction in the same pixel tocorrect a defective pixel, and a detection unit for detecting adefective pixel in the image pickup area, wherein, when it is detectedthat a signal from one photoelectric conversion section in the samepixel requires correction, the detection unit controls the secondcorrection unit so that signals from other photoelectric conversionsections in the same pixel are also corrected, and detects a defectivepixel on the basis of a signal before being input into the firstcorrection unit.

[0020] The aforementioned objects of the present invention will beapparent from the following drawings and detailed description on thebasis of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 is a configuration diagram showing an image pickupapparatus according to a first embodiment of the present invention;

[0022]FIG. 2 is a flow chart for explaining correction processing in thefirst embodiment;

[0023]FIG. 3 is a diagram for explaining defect correction of R color;

[0024]FIG. 4 is a diagram for explaining defect correction of G color;

[0025]FIG. 5 is a diagram for explaining defect correction of B color;

[0026]FIG. 6 is a configuration diagram showing an image pickupapparatus according to a second embodiment of the present invention;

[0027]FIG. 7 is a flow chart for explaining correction processing in thesecond embodiment; and

[0028]FIG. 8 is a diagram for explaining a pixel having photodiodes inthe depth direction of a semiconductor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, embodiments according to the present invention willbe described referring to the drawings.

[0030] First embodiment

[0031]FIG. 1 shows a configuration of an image pickup apparatus (digitalcamera) according to a first embodiment of the present invention.

[0032] In FIG. 1, numeral 1 denotes an image pickup optical system,numeral 2 denotes a shutter, numeral 3 denotes an image pickup element,numeral 4 denotes an amplifying circuit, numeral 5 denotes an A/Dconverter, numeral 6 denotes a signal pre-processing unit, numeral 7denotes a color separation switch, numeral 8 denotes a changeoverswitch, numeral 9 denotes an image memory, numeral 10 denotes asubtractor, numeral 11 denotes a defect data memory, numeral 12 denotesa defect correction processing unit, numeral 13 denotes a signalpost-processing unit, numeral 14 denotes a recording unit, and numeral15 denotes a display unit.

[0033] Correction processing according to the first embodiment of thepresent invention will be described using FIG. 1 and a flow chart ofFIG. 2.

[0034] The image pickup element 3 is an image pickup element having animage pickup area in which a plurality of pixels each having photodiodeswhich are a plurality of photoelectric conversion sections are arrangedin the depth direction of a semiconductor as shown in FIG. 8. Defectdata (position of defective pixel) of the image pickup element 3detected in advance is stored in the defect data memory 11. This defectdata is obtained by detecting a position of a pixel which exceeds acertain threshold value, from an image picked up, for example, in thelight-shielded state.

[0035] In the present embodiment, at first, an object is picked up(S101). The object image formed by the image pickup optical system 1 isconverted into an electric signal by the image pickup element 3 via theshutter 2 controlled and driven so as to have the appropriate amount ofexposure. The object image is amplified or level-shifted so as to beappropriate for an input range of the A/D converter 5 in the amplifyingcircuit 4. An analog signal is digitized in the A/D converter 5. A blacklevel adjustment such as clamp is performed on the digitized image databy the signal pre-processing unit 6. At this time, three changeoverswitches 8 are connected to the image memories 9, respectively.

[0036] The color separation switch 7 is driven so as to store the imagesignals output from the image pickup element 3 into the image memoriescorresponding to the respective colors. In other words, a signal from aphotodiode at the deepest position in the depth direction is stored inthe image memory R, a signal from a photodiode at the second deepestposition in the depth direction is stored in the image memory G, and asignal from a photodiode at the shallowest position in the depthdirection is stored in the image memory B. Thereby, the image data ofthe color-separated object image is stored in the image memories 9(S102).

[0037] Thereafter, correction processing using the subtractors 10 isperformed (S103). Here, at first, image pickup of the same accumulationtime as that of image pickup of the object is performed under acondition that the shutter 2 is closed, that is, the image pickupelement 3 is light-shielded. At this time, the three changeover switches8 are connected to the direction opposite to the image memories 9, thatis, the subtractors 10. Further, the image memories 9 output the imagedata of the object image at the same position as that of thelight-shielded image data to the subtractors 10. Thereby, the image dataof the object image whose unevenness or slight defect resulting from adark current of the image pickup element has been corrected is outputfrom the subtractors 10. Further, the correction is independentlyperformed for each color separated in the image pickup element 3. Inother words, a dark current signal from the photodiode at the deepestposition in the depth direction is subjected to differential processingrelative to the signal stored in the image memory R, a dark currentsignal from the photodiode at the second deepest position in the depthdirection is subjected to differential processing relative to the signalstored in the image memory G, and a dark current signal from thephotodiode at the shallowest position in the depth direction issubjected to differential processing relative to the signal stored inthe image memory B.

[0038] As described above, the image pickup apparatus according to thepresent embodiment has said image pickup area (image pickup element 3)where a plurality of pixels each having at least first, second, andthird photoelectric conversion sections (corresponding to BLUE PHOTONCOLLECTION, GREEN PHOTON COLLECTION, and RED PHOTON COLLECTION,respectively, in FIG. 8) are arranged in the depth direction of asemiconductor, and a first correction unit consisting of the imagememories 9 and the subtractors 10 for performing differential processingbetween a signal obtained in the first photoelectric conversion sectionin case that said image pickup area is light-shielded and a signalobtained in the first photoelectric conversion section by picking up anobject image in said image pickup area, differential processing betweena signal obtained in the second photoelectric conversion section in casethat said image pickup area is light-shielded and a signal obtained inthe second photoelectric conversion section by picking up an objectimage in said image pickup area, and differential processing between asignal obtained in the third photoelectric conversion section in casethat said image pickup area is light-shielded and a signal obtained inthe third photoelectric conversion section by picking up an object imagein said image pickup area, so that correction can be performed even whendifferent noises are present for the respective colors.

[0039] In the defect correction processing unit 12, defect correctionprocessing is performed on the basis of the defect data stored in thedefect data memory 11 in advance (S104). The defect-corrected image datais subjected to color processing and the like in the signalpost-processing unit 13, and then transmitted to the recording unit 14or the display unit 15 so as to be recorded or displayed therein.

[0040] The defect correction processing in step S104 will be describedwith reference to FIGS. 3, 4, and 5. FIG. 3 shows a vicinity of m-thcolumn and n-th row of the R color of the image signal of the objectimage color-separated and stored in the image memory. In this example,the R color pixel at m-th column and n-th row is detected as a defect inadvance and stored in the defect data memory 11. In the defectcorrection processing unit 12, position information of the defect isread by the defect data memory 11, and the image data of the defectposition is replaced and interpolated by the image data of the samecolor as the neighboring pixels. In the case of FIG. 3, since the Rcolor pixel at m-th column and n-th row is defective, for example, theimage data Ra of the R color pixel at m−1-th column and n-th row and theimage data Rc of the R color pixel at m+1-th column and n-th row areused, so that the average value therebetween is assumed as the imagedata of the R color pixel at m-th column and n-th row.

[0041]FIGS. 4 and 5 show vicinities of m-th column and n-th row of theimage signals of the object image of the G color and the B color,respectively. The pixels Gb and Bb at m-th column and n-th row in FIGS.4 and 5 have not been detected as defects in advance. However, in thepresent invention, when other colors in the same pixel are defective asin FIG. 3, defect correction is similarly performed on the image data ofall the colors. Therefore, the image data Gb of the G color is replacedwith the average value between Ga and Gc. Similarly, the image data Bbof the B color is replaced with the average value between Ba and Bc. Inthis manner, when the image signal of any one of colors of the samepixel has been detected as a defect in advance, similar defectcorrection processing is performed on the image signals of all thecolors, so that image deterioration resulting from influence in terms ofthe structure on a color signal at the depth where there is no defectcan be prevented.

[0042] As described above, the image pickup apparatus according to thepresent embodiment has said image pickup area where a plurality ofpixels each having a plurality of photoelectric conversion sections arearranged in the depth direction of a semiconductor, and a secondcorrection unit consisting of the defect data memory 11 and the defectcorrection processing unit 12 for correcting each of signals from theplurality of photoelectric conversion sections in the depth direction inthe same pixel to correct defective pixel, so that defect correction canbe accurately performed.

[0043] In the embodiment described above, the front stage of the imagememory 9 is configured so that signals are transmitted with time-series,but the amplifying circuit 4, the A/D converter 5, and the signalpre-processing unit 6 may be provided in parallel so that the signalsare output from the image pickup element to the image memory R, theimage memory G, and the image memory B in parallel. In this case, thesignals from the three photoelectric conversion sections of the samepixel arranged in the depth direction of a semiconductor are read fromthe image pickup element in parallel.

[0044] Second embodiment

[0045]FIG. 6 shows a configuration of an image pickup apparatusaccording to a second embodiment of the present invention. In FIG. 6,same components as those in FIG. 1 are denoted with the same referencenumerals, and description thereof will be omitted. Numeral 16 denotes adefect detection circuit, and numeral 17 denotes a defect data mixingcircuit.

[0046] Correction processing according to the second embodiment of thepresent invention will be described with reference to FIG. 6 and a flowchart of FIG. 7.

[0047] The image pickup element 3 is an image pickup element having athree-layer photodiode structure described as a conventional example.The defect detection circuit 16 detects a defect resulting from a darkcurrent, from image data picked up in case that the shutter 2 is closed,that is, the image pickup element 3 is light-shielded. The methodtherefor is to determine as a defect a pixel whose ratio or differencebetween the image data value of a detection target pixel and the averagevalue of the image data of the neighboring pixels is not less than apredetermined value, and to output a result as defect data.

[0048] Even when any one of colors of the same pixel is defective, thedefect data detected for each color is combined into the data of defectpixel position, by the defect data mixing circuit 17.

[0049] In the present embodiment, at first, an object is picked up(S201). The object image formed in the image pickup optical system 1 isconverted into an electric signal in the image pickup element 3 via theshutter 2 controlled and driven so as to have the appropriate amount ofexposure. The object image is amplified or level-shifted so as to beappropriate for an input range of the A/D converter 5 in the amplifyingcircuit 4. An analog signal is digitized in the A/D converter 5. A blacklevel adjustment such as clamp is performed for the digitized image datain the signal pre-processing unit 6. At this time, the three changeoverswitches 8 are connected to the image memories 9, respectively.

[0050] The color separation switch 7 is driven so as to store the imagesignals output from the image pickup element 3 into the image memoriescorresponding to the respective colors. Thereby, the image data of thecolor-separated object image is stored in the image memories 9 (S202).

[0051] Thereafter, correction processing using the subtractors 10 isperformed (S203). Here, at first, image pickup of the same accumulationtime as that of image pickup of the object is performed under acondition that the shutter 2 is closed, that is, the image pickupelement 3 is light-shielded. At this time, the three changeover switches8 are connected to the direction opposite to the image memories 9, thatis, the subtractors 10. At the same time, the light-shielded imaged datais input into the defect detection circuits 16 for each color.

[0052] The defect detection circuit 16 performs the aforementioneddefect detection to output the defect data for each color (S204).Further, the image memories 9 output to the subtractors 10 the imagedata of the object image at the same position as that of thelight-shielded image data. Thereby, the image data of the object imagewhose unevenness or slight defect resulting from a dark current of theimage pickup element has been corrected is output from the subtractors10. Further, the correction is independently performed for each colorseparated in the image pickup element 3, so that correction can beperformed even when different noises are present for the respectivecolors.

[0053] The defect correction processing unit 12 performs defectcorrection processing on the basis of the defect data after the defectdata output from the three defect detection circuits 16 is combined inthe defect data mixing circuit 17 (S205). The defect-corrected imagedata is subjected to color processing and the like in the signalpost-processing unit 13, and then transmitted to the recording unit 14or the display unit 15 so as to be recorded or displayed therein. Since,after the defect data of all the colors is combined in the defect datamixing circuit 17, correction is performed by the defect correctionprocessing units 12, image deterioration resulting from influence interms of the structure on a color signal at the depth where there is nodefect can be prevented. Furthermore, defect correction can be performedwithout preparing the defect data in advance.

[0054] As described above, the image pickup apparatus according to thepresent embodiment has said image pickup area where a plurality ofpixels each having a plurality of photoelectric conversion sections arearranged in the depth direction of a semiconductor, and a secondcorrection unit consisting of the defect detection circuits 16, thedefect data mixing circuit 17, and the defect correction processingunits 12 for performing correction of each signal from the plurality ofphotoelectric conversion sections in the depth direction in the samepixel to correct a defective pixel, so that defect correction can beaccurately performed.

[0055] In the aforementioned embodiment, the front stage of the imagememory 9 is configured so that signals are transmitted with time-series,but the amplifying circuit 4, the A/D converter 5, and the signalpre-processing unit 6 may be provided in parallel so that the signalsare output from the image pickup element to the image memory R, theimage memory G, and the image memory B in parallel. In this case, thesignals from the three photoelectric conversion sections of the samepixel, arranged in the depth direction of a semiconductor are read fromthe image pickup element in parallel. Furthermore, the defect datadetection is performed after the object image pickup, but may beperformed, for example, after the image pickup apparatus is turned on,alternatively, before or after the object is picked up, or when there istime for control of the image pickup apparatus.

[0056] In addition, in the first and second embodiments described above,the number of colors of the image pickup element to be separating in thedepth direction of a semiconductor is three of R, G, and B, but may betwo or more. In other words, the image pickup element is configured tohave at least first and second photoelectric conversion sectionsarranged in the depth direction of a semiconductor.

[0057] Further, in the above first and second embodiments, there isshown the circuit having both a circuit for correcting a dark current(first correction unit) and a circuit for correcting a defective pixel(second correction unit), but the circuit may be configured to haveeither one circuit.

[0058] Other embodiments

[0059] In the above embodiments, there is described an example where thepresent invention is applied to a digital camera, but the presentinvention is not limited thereto, and can be applied to otherapparatuses such as digital video camera, as long as the image pickupelement used in the above embodiments is available.

[0060] Further, in the above embodiments, the first correction unit andthe second correction unit for performing processings according to thepresent invention are configured with circuits, but the presentinvention is not limited thereto, and all or part of these units may beconfigured on the memory by software.

[0061] In other words, it goes without saying that the objects of thepresent invention can be accomplished by supplying a storage mediumstoring a program code of a software for realizing the functions of theabove embodiments therein to a system or an apparatus so that a computer(or CPU or MPU) in the system or the apparatus reads the program codestored in the storage medium.

[0062] In this case, the program code itself read from the storagemedium realizes the functions of the above embodiments, so that thestorage medium storing the program code therein configures the presentinvention.

[0063] As a storage medium for supplying a program code, there may beemployed, for example, a flexible disk, a hard disk, an optical disk, amagneto optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatilememory card, a ROM, and the like.

[0064] Further, it goes without saying not only that the program coderead by the computer is executed so that the functions of the aboveembodiments can be realized but also that an OS (operating system)running on the computer performs part of or all the actual processings,so that the functions of the above embodiments can be realized.

[0065] Furthermore, it goes without saying that, after the program coderead form the storage medium is written into a memory provided in afunction extension board inserted into the computer or a functionextension unit connected to the computer, the CPU or the like providedin the function extension board or the function extension unit performspart of or all the actual processings on the basis of an instruction ofthe program code, so that the functions of the above embodiments can berealized.

[0066] Hereinbefore, the present invention is described by the preferredembodiments, but the present invention is not limited to the aboveembodiments, and can be variously modified within the range described inthe claims.

What is claimed is:
 1. An image pickup apparatus comprising: an imagepickup area where a plurality of pixels each having at least first andsecond photoelectric conversion sections are arranged in a depthdirection; and a first correction unit which performs differentialprocessing between a signal obtained in the first photoelectricconversion section in case that said image pickup area is light-shieldedand a signal obtained in the first photoelectric conversion section bypicking up an object image in said image pickup area, and differentialprocessing between a signal obtained in the second photoelectricconversion section in case that said image pickup area is light-shieldedand a signal obtained in the second photoelectric conversion section bypicking up an object image in said image pickup area.
 2. An image pickupapparatus comprising: an image pickup area where a plurality of pixelseach having a plurality of photoelectric conversion sections arearranged in a depth direction; and a second correction unit whichcorrect each of signals from the plurality of photoelectric conversionsections arranged in the depth direction in the same pixel to correct adefective pixel.
 3. An image pickup apparatus according to claim 2,comprising a storage unit which stores a position of a defective pixelin said image pickup area, wherein said second correction unit performscorrection on the basis of data stored in the storage unit.
 4. An imagepickup apparatus according to claim 2, comprising a detection unit whichdetects a defective pixel in said image pickup area, wherein, when it isdetected that a signal from one photoelectric conversion section in thesame pixel requires correction, said detection unit controls said secondcorrection unit so that signals from the other photoelectric conversionsections in the same pixel are also corrected.
 5. An image pickupapparatus comprising: an image pickup area where a plurality of pixelseach having at least first and second photoelectric conversion sectionsare arranged in a depth direction; a first correction unit whichperforms differential processing between a signal obtained in the firstphotoelectric conversion section in case that said image pickup area islight-shielded and a signal obtained in the first photoelectricconversion section by picking up an object image in said image pickuparea, and differential processing between a signal obtained in thesecond photoelectric conversion section in case that said image pickuparea is light-shielded and a signal obtained in the second photoelectricconversion section by picking up an object image in said image pickuparea; a second correction unit provided in the rear stage of the firstcorrection unit, which performs correction each of signals from thefirst and second photoelectric conversion sections arranged in the depthdirection in the same pixel to correct a defective pixel; and adetection unit which detects a defective pixel in said image pickuparea, wherein, when it is detected that a signal from one photoelectricconversion section in the same pixel requires correction, said detectionunit controls said second correction unit so that signals from the otherphotoelectric conversion sections in the same pixel are also corrected,and detects a defective pixel on the basis of a signal before beinginput into said first correction unit.
 6. An image pickup method usingan image pickup area where a plurality of pixels each having at leastfirst and second photoelectric conversion sections are arranged in adepth direction, comprising: an image pickup step of picking up anobject image in said image pickup area and obtaining signals from thefirst and second photoelectric conversion sections in case that saidimage pickup area is light-shielded; and a first correction step ofperforming differential processing between a signal obtained in thefirst photoelectric conversion section in case that said image pickuparea is light-shielded and a signal obtained in the first correctionunit by picking up an object image in said image pickup area, anddifferential processing between a signal obtained in the secondphotoelectric conversion section in case that said image pickup area islight-shielded and a signal obtained in the second photoelectricconversion section by picking up an object image in said image pickuparea.
 7. An image pickup method using an image pickup area where aplurality of pixels each having a plurality of photoelectric conversionsections are arranged in a depth direction, comprising: an image pickupstep of picking up an object image using said image pickup area; and asecond correction step of correcting each of signals obtained from theplurality of photoelectric conversion sections arranged in the depthdirection in the same pixel in said image pickup step, therebycorrecting a defective pixel.
 8. An image pickup method using an imagepickup area where a plurality of pixels each having at least first andsecond photoelectric conversion sections are arranged in a depthdirection, comprising: an image pickup step of picking up an objectimage in said image pickup area and obtaining signals from the first andsecond photoelectric conversion sections in case that said image pickuparea is light-shielded; a first correction step of performingdifferential processing between a first signal obtained in the firstphotoelectric conversion section in case that said image pickup area islight-shielded and a signal obtained in the first photoelectricconversion section by picking up an object image in said image pickuparea and differential processing between a second signal obtained in thesecond photoelectric conversion section in case that said image pickuparea is light-shielded and a signal obtained in the second photoelectricconversion section by picking up an object image in said image pickuparea; a detection step of detecting a defective pixel in said imagepickup area on the basis of the first and second signals; and a secondcorrection step of correcting each of signals from the first and secondphotoelectric conversion sections arranged in the depth direction in thesame pixel in accordance with a detection result in said detection step.